Young teens in thoungs. If you really don't want her to wear thongs, buy a pair or two for yourself and let her know that you're wearing them--she wouldn't homemade wooden pony bdsm to wear them then since you wear them!
Join protests tomorrow.
For decades us women wore regular undies and had no problems with how our fanny looked until thongs came about.
Teens I Need Help!
Try your hardest to have open, honest and mature as possible discussions with her and you will have so many fewer troubles in the future.